Urban runoff study motivates change in landscape practices

The Issue

Master gardener collecting water samples in Sacramento County.

Recent droughts and expanding urban populations place increasing pressure on California’s water supplies. In residential areas, outdoor water use, primarily for landscapes, comprises 50 percent or more of total water use. It is commonplace to see excess water gushing down storm drains from poorly aimed sprinklers, broken sprinkler heads, and a larger volume of water applied than the soil can absorb.

The runoff water can carry pesticides, fertilizers and other waste into waterways, causing a detrimental effect on the health of the aquatic life in rivers, lakes and bays.

What Has ANR Done?

In a study funded by CALFED and the State Water Resources Control Board, University of California researchers examined the runoff from eight neighborhoods in Sacramento and Orange counties. Water runoff samples were collected regularly during the irrigation season and during the first rains of each storm season. The samples were analyzed for 11 pesticides, fertilizers, other pollutants and pathogens.

In both counties, UC master gardeners developed activities for homeowners to improve landscape management practices related to water, fertilizer, and pesticide use. The aim was to reduce or eliminate pollution runoff.

The Payoff

Tools for Management Practices and Urban Planning

Runoff flow in both counties showed consistent water waste from normal landscape irrigation. In Northern California, irrigation runoff was nearly five times higher than storm runoff, indicating poor outdoor water management in the dry season. In general, pesticides and pathogen indicators were found in all samples.

This data helped water agencies develop customer programs on managing landscapes. Master gardener outreach improved the landscape practices of homeowners. The flow data also is being used by a team of UC researchers to develop a model for urban planners and developers to reduce water runoff and runoff pollutants in new and existing urban landscapes.